- Mar 30, 2007
A variety of species of clostridium are associated with invasive infection in humans i.e. C. perfringens, novyi, septicum, histolyticum, tertium, bifermentans, sporogenes. They are not highly pathogenic when introduced into healthy tissues; but in the presence of tissue injury, in particular damaged muscle, they can cause a rapidly progressive devastating infection characterised by the accumulation of gas and the extensive destruction of muscle and connective tissue. Pathogenesis is due to the production of various toxins with necrotising, haemolytic or other destructive properties.
There are three types of clostridial wound infection: wound contamination, anaerobic cellulitis, and true myonecrosis (gas gangrene). 80 to 90% of isolations of C. perfringens from hospital represent wound contamination which does not herald invasive infection. Anaerobic cellutitis is a clostridial infection that does not involve the muscle and is much less aggressive than gas gangrene. Germination occurs in damaged tissue where damage to the blood supply has reduced the supply of oxygen. The vegetative bacilli multiply and anaerobic cellulitis develops after several days. The marked gas formation is detectable by the resulting crepitus. Gas gangrene is an intensively aggressive highly lethal infection, primary of muscle. After the germination of clostridial spores in the injured muscle, bacterial multiplication and toxin production occur. A self-perpetuating cycle of progressive tissue injury ensue. The onset of the disease is sudden, usually following an onset of 6 to 72 hours after injury or abdominal surgery. Of the six clostridial species capable of producing gas gangrene, C. perfringens account for the majority of cases.
[FONT="]Symptoms:[/FONT][FONT="] Gas gangrene produces severe pain in the infected area. Initially, the area is swollen and pale, but eventually turns red, then bronze, and finally blackish green. Large blisters often form. Gas bubbles may be visible in the blister fluid or may be felt under the skin. The odor of any wound drainage is described as sweet or mousy, unlike the putrid odor typical of other anaerobic infections.[/FONT]
[FONT="]As the infection progresses, the person becomes sweaty and very anxious; vomiting may also occur. Rapid heart rate and rapid breathing are common. These effects are caused by toxins produced by the bacteria. Typically, the person remains very alert until late in the illness, when very low blood pressure (shock) and coma develop, followed rapidly by death.[/FONT]
[FONT="]Diagnosis: [/FONT][FONT="]The initial diagnosis of gas gangrene is based on the person's symptoms and a physical examination. Finding gas bubbles in the muscle tissue on x-ray increases a doctor's suspicion of a clostridial infection, but gas bubbles may also occur with non-clostridial anaerobic infections. Examination of secretions from the wound under a microscope may reveal the clostridia, and cultures can confirm their presence—but because gas gangrene is so rapidly fatal, treatment is always begun before the culture results are available.[/FONT]
[FONT="]Treatment: Without treatment, gas gangrene is fatal within 48 hours. Even with treatment, death occurs in about one of eight people with infection of a limb and in about two of three people with infection on the trunk.[/FONT]
[FONT="]If gas gangrene is suspected, treatment must begin immediately. High doses of antibiotics, typically penicillin and clindamycinSome Trade Names
, are given, and all dead and infected material is removed surgically. About one of five people with gas gangrene in a limb requires amputation of the infected limb. Treatment in a high-pressure oxygen (hyperbaric oxygen) chamber is of uncertain value; moreover, such chambers are not readily available.[/FONT]